1. Field of the Invention
The present invention relates to a large-sized hydraulic working machine in which a plurality of hydraulic pumps are connected in parallel and employed as one large hydraulic pump equivalently, and more particularly to a pump failure alarm system for a hydraulic working machine which determines whether the individual hydraulic pumps are good or not, and gives an alarm to an operator in the event of a pump failure.
2. Description of the Prior Art
In hydraulic working machines such as hydraulic excavators, one or more hydraulic pumps are driven by one or more prime movers and one or more hydraulic actuators are driven by hydraulic fluids delivered from the hydraulic pumps. When installed in a hydraulic working machine, a hydraulic pump having the size and capacity in match with a working ability of the hydraulic working machine is selected. It is however general in a large-sized hydraulic working machine that a plurality of hydraulic pumps are connected in parallel and employed as one large hydraulic pump equivalently from the viewpoints of cost and reliability. In that case, the number of hydraulic pumps to be installed in a hydraulic working machine is determined depending on a maximum flow rate demanded by hydraulic actuators of the hydraulic working machine.
JP, B, 4-29816 discloses a hydraulic excavator as one example of the known art relating to such a large-sized hydraulic working machine. Four hydraulic pumps driven by two engines are disposed in a hydraulic circuit of the disclosed hydraulic excavator. Of the first to fourth hydraulic pumps, the first and second ones are driven by a first engine, while the third and fourth ones are driven by a second engine. Delivery circuits of the first and third hydraulic pumps are joined with each other and led to a first group of control valves, and delivery circuits of the second and fourth hydraulic pumps are joined with each other and led to a second group of control valves. A hydraulic fluid is thereby supplied to a hydraulic actuator associated with each corresponding group of control valves.